type about:config in the URL bar and hit Enter
If you see the warning, you can confirm that you want to access that page.
Filter = general.useragent.extra.firefox
Right-click that preference and select Reset
Then restart Firefox

If that doesn't solve your Hotmail problem, see Windows Live / Hotmail support.

Your UserAgent string in Firefox is messed up by another program that you installed. URIAPRO[]
[http://en.wikipedia.org/wiki/User_Agent]
type '''about:config''' in the URL bar and hit Enter
''If you see the warning, you can confirm that you want to access that page.''
Filter = '''general.useragent.extra.firefox'''
Right-click that preference and select '''Reset'''
Then restart Firefox
If that doesn't solve your Hotmail problem, see Windows Live / Hotmail support.